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A stone, of mass m , falls vertically downwards under gravity through still water. The initial speed of the stone is u . Find an expression for v at time t .

Ma = mg - Lmv 2) dv/dt = g-Lv 3)-1/L *(ln(g -Lv)/(g - Lu)) = t 4) g - Lv/ g - Lu = e -Lt 5) Rearrange to.... v = 1/L *(g-(g - Lu) e -Lt ) Missed some steps as it was relatively long, can perform this fully i...
JW
Answered by Joseph W. • Maths tutor
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What is the cosine rule and how do I use it?

The cosine rule, a 2 =b 2 +c 2 -2bccosA, where a, b, & c are the sides of a triangle and A is the angle opposite side a, is the general version of Pythagoras' Theorem and applies to any triangle, not jus...
MQ
Answered by Matt Q. • Maths tutor
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What is price elasticity of demand?

Price elasticity of demand (PED) measures the responsiveness of demand in relation to a change in price. The formula for PED is %change in quantity demand / %change in price. If a good has an elastic PED it ...
AL
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How do I structure an essay question?

In history essays you need to show that you understand the question you are being asked and that you can illustrate several different interpretations, backing each with evidence. An introduction is needed to...
JO
Answered by Joshua O. • History tutor
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Show that a pendulum undergoes simple harmonic motion (SHM). State your assumptions. The pendulum is made up of a light inextensible string, attached to a ceiling at one end and with a particle of mass m attached to the other end.

Begin with a diagram of the system, and definition of directions. Vertically up and clockwise rotations are positive. It must be recalled that in SHM force is proportional to displacement from equqilibrium. ...
LK
Answered by Luke K. • Physics tutor
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